Catalytic reforming of petroleum hydrocarbons with an alumina-chromium oxide catalyst containing bismuth oxide and an alkali metal oxide



1 2,967,821 CATALYTIC REFORMING F PETROLEUM HY-' DROCARBONS WITH AN'ALUMINA-CHROMIUM- OXIDE CATALYST CONTAINING BISMUTH Thisinvention relates to the catalytic reforming of petroleum hydrocarbons for the production of aromatics, motor gasoline and the like.

The catalytic reforming of petroleum hydrocarbons, for example naphtha fractions, toproduce fractions of increased octane number is a Well-known and established art. Various catalysts have been proposed as reforming catalysts; those most commonly employed comprise compounds of metals of group VI or group VIII of the periodic table on a. support consisting of or containing alurninium oxide. Thus the conversion of aliphatic hydrocarbons to aromatic hydrocarbons. has been described using a catalyst consisting of aminor proportion of chromium oxide supported on a major proportion of. alumina. It has further been proposed to convert parafiinic and olefinic hydrocarbons in light petroleum fractions into aromatic hydrocarbons using a catalyst comprising: a cyclizing metal compound such as chromium oxide supported on alumina and promoted with 2.5 %-20% of'a rare earth element and 6%-30% of potassium or rubidi um or caesium, both percentages being based on the weight of the cyclizing metal compound.

The object of the present invention is further to improve'reforming. processes using. chromia-alumina catalyst.

According to the present invention, a feedstock consisting of or containing non-aromatic hydrocarbons is contacted with a catalyst comprising chromia, aluminaand aminor proportion of bismuth, at a temperature of from 450 to 580 C. and a pressure up to 50 p.s.i.g. to yield a product with a higher aromatic content than the feedstock, there being no addition of hydrogen, whether extraneous or recycled, to the reaction zone.

The present process besides yielding anormally liquid product having an appreciable content of aromatics and some olefins, also produces appreciable quantities-of a hydrogen-rich gas,.which.is available. as a valuable byproduct. .The term a pressure. up to 50 p.s.i.g.- includes atmospheric pressure or below, atmospheric pressure being, in fact, preferred. A temperature in the vicinity of 525 C. is particularly preferred and the space velocity may be from 0.1 to 1.0 v./v./hr. of liquid feedstock.

The bismuth in the catalyst is preferably present as an oxide and preferably there is also a minor proportion of an alkali metal compound, for example a potassium compound, particularly the oxide.

The relative proportions of the catalyst components by weight of total catalyst material stable at 1020 F., are, preferably, within the limits:

Percent Chromium oxide to 25 Bismuth (as oxide) 0.1 to 5 Alkali metal (as oxide) 0.1 to 5 Alumina Balance States Patent 9 The catalyst may be used in the form-ofa fixed bed'," a moving bed or a fluidizedbed. Since it is readilyref generated by burning oifcarbonaceous depo'sits in a} stream of oxygen-containing gas, it isparticularly suitablek for fluidized or moving bed processes.

The process makes available a large quantity-of hydrog gen-rich gas as a valuable by-product.

The feedstock used should boil within the'gasoline or naphtha range, anda particularly preferred fract'ion'cork sists predominantly of amixtu'reof C -C5 hydrocarbons.

I Thus according to one ernbodiment of the invention the feedstock may be a straight-run feedstock,particulanly a lower-boiling straight-run fractioncommonly known as primary flash distillate. By treatment according to the presentinventiontgasoline blending components of high octane number and high volatility mayjbe pre: pared from suchfeedstockain particular gasoline blending components having a research octane number ,(clea'r')j of at least and a volatility of: at least 70% evaporated at C.

According to a further embodiment, the feedstock may be the product of a previous catalytic reforming process so that the present invention includes a two-stagereforming process designed to produce aromatics and high octane. gasoline fractions with preferably a research octane number (clear) of the order of 100. Any convenient reforming process may be used'as the first stage, but those employing a. catalyst of platinum on a support' containing aluminium oxide with or without halogenare: preferred, such processes being hereinafter. referred. to, as platinum reforming processes and the products as plat inum reformates.

With a two-stage process, the whole of the reformate from the first stage may be reformed in the secondstage but since the higher-boiling, end. is rich in aromatics which are not susceptible to further upgrading, the reformate is preferably fractionated to give a lower-boiling relatively aromatic-free fraction which is subjected to the further treatment. Alternatively the reformate may be solventextractedand the rafiinate or a fraction thereof subjected to the further treatment. If desired, the prod-' uct may be recombined with the higher boiling fraction or the solvent extract as the case may be, but it"r'nayal'so be combined with other high octane QQII'IPQIICIIIS fQEUCK. ample heavy cat. cracked gasoline or alky late;

The catalyst may be prepared by any conyenient method for example, by impregnation of alumina with a solution containing chromium, bismuth andv stea ing potassium; An example of catalyst preparationisgiyet l.

in Example 1 below.

EXAMPLE 1 160 g. of granulated (4-8 mesh BSS) alumina, roasted at 550 C. for 2 hours and stored under vacuum, were impregnated With a solution of 23 g. Analar grade chromium trioxide, 4 g. Analar grade potassium nitrate and 3.9 g. bismuth nitrate in 40 ml. of distilled water and 40 ml. Analar grade concentrated nitric acid.

The solution was wholly absorbed. The catalyst was dried at C. for 15 hours and roasted at 550 C. for 2 hours.

The invention is illustrated by the following examples.

EXAMPLE 2 A reformate obtained by hydroforming a naphtha fractron over a catalyst consisting of platinum, alumina and 2,967,821 I Patented Jan- 1 combined halogen, was split into light and heavy frac-. tions, the light fraction having an end boiling point of 108 C. and a research octane number (clear) of 76.1. This light reformate was further reformed under the following conditions:

Pressure Atmospheric Space velocity v./v./hr- 0.2 Recycle gas None Processing period hours Reaction temperature C 530 Four runs were carried out under these conditions using difierent catalysts as follows:

(1) chromium oxide on alumina.

(2) 10% chromium oxide on alumina with 1% cerium oxide and 1% potassium oxide.

(3) 10% chromium oxide on alumina with 1% bismuth oxide.

(4) 10% chromium oxide on alumina with 1% bismuth oxide and 1% potassium oxide.

All percentages are by weight of material stable at 1020 F. Comparative data for the four runs are shown in Table 1.

I Octane numbers above 100 were calculated according to the following equation:

(where PN==Army and Navy Performance Number).

EXAMPLE 3 A light straight run gasoline having an ASTM boiling range of 41-87 C. and an octane number, research, clear, of 63.3 was treated under the following process conditions:

Pressure Atmospheric Space velocity v./v./hr 0.2 Recycle gas None Runs were carried out at different temperatures using the catalysts of run 2 and run 4 of Example 2 respectively. The results are set out in Table 2 below.

We claim:

1. A process for the treatment of a feedstock c0nsist ing essentially of a mixture of C to C non-aromatic hydrocarbons to etfect a dehydrogenation or dehydrocyclization thereof comprising contacting the feedstock in a reaction zone in the presence of a catalyst consisting essentially of from 5 to 25% chromium oxide, from 0.1 to 5% of bismuth, expressed as the oxide, and 0.1 to 5% of an .alkali metal, expressed as the oxide, and the balance alumina, at a temperature of from 450-580 C. and a pressure not in excess of about 50 p.s.i.g., and a space velocity of 0.1 to 1 v./v./hr., and in the absence of added hydrogen to the reaction zone, and recovering a product of increased aromatic content.

2. A process for the treatment of a feedstock consisting essentially of a mixture of C to C non-aromatic hydrocarbons to effect a dehydrogenation or dehydrocyclization comprising contacting the feedstock in a re action zone in the presence of a catalyst consisting essentially of 5 to 25% chromium oxide, from 0.1 to 5% of bismuth, expressed as the oxide, and 0.1 to 5% of an alkali metal, expressed as the oxide, and the balance alumina, at a temperature of approximately 525 C., at a pressure not in excess of about 50 p.s.i.g., at a space velocity of 0.1 to l v./v./hr., and in the absence of added hydrogen to the reaction zone, and recovering a product of increased aromatic content.

3. A process in accordance with claim 1, wherein the feedstock is a straight run distillate consisting essentially of a mixture of C to C non-aromatic hydrocarbons.

4. A process in accordance with claim 1, wherein the feedstock is a portion of a catalytic reformate, said portion consisting essentially of a mixture of C to C nonaromatic hydrocarbons.

5. A process in accordance with claim 1, wherein the feedstock is a portion of the platinum reformate, said portion consisting essentially of a mixture of C to C non-aromatic hydrocarbons.

References Cited in the file of this patent UNITED STATES PATENTS 2,635,082 Smith Apr. 14, 1953 2,645,605 Lang et al July 14, 1953 2,651,597 Corner et a1. Sept. 8, 1953 

1. A PROCESS FOR THE TREATMENT OF A FEEDSTOCK CONSISTING ESSENTIALLY OF A MIXTURE OF C5 TO C7 NON-AROMATIC HYDROCARBONS TO EFFECT A DEHYDROGENATION OR DEHYDROCYCLIZATION THEREOF COMPRISING CONTACTING THE FEEDSTOCK IN A REACTION ZONE IN THE PRESENCE OF A CATALYST CONSISTING ESSENTIALLY OF FROM 5 TO 25% CHROMIUM OXIDE, FROM 0.1 TO 5% OF BISMUTH, EXPRESSED AS THE OXIDE, AND 0.1 TO 5% OF AN ALKALI METAL, EXPRESSED AS THE OXIDE, AND THE BALANCE ALUMINA, AT A TEMPERATURE OF FROM 450-580*C. AND A PRESSURE NOT IN EXCESS OF ABOUT 50 P.S.I.G., AND A SPACE VELOCITY OF 0.1 TO 1 V./V./HR., AND IN THE ABSENCE OF ADDED HYDROGEN TO THE REACTION ZONE, AND RECOVERING A PRODUCT OF INCREASED AROMATIC CONTENT. 